Polishing apparatus and method of polishing a subject
A polishing apparatus. The polishing apparatus has an abrasive cloth and a table to rotate the abrasive cloth. A holder holds a subject to be polished against the abrasive cloth. A discharger discharges a polishing solution from the abrasive cloth after the polishing solution passes between the abrasive cloth and the subject.
This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2004-089296 filed on Mar. 25, 2004, the entire contents of which are incorporated herein by reference.
BACKGROUND1. TECHNICAL FIELD
This invention relates to a polishing apparatus and a method of polishing a subject, in particular, to a polishing apparatus using chemical mechanical polishing (CMP) method and a method of polishing a subject using the CMP method.
2. DESCRIPTION OF THE RELATED ART
The method of supplying polishing solution 72 shown in
There is a polishing apparatus consistent with the present invention. The apparatus comprises an abrasive cloth, a table to rotate the abrasive cloth, a holder configured to hold a subject to be polished against the abrasive cloth, and a discharger to discharge a polishing solution from the abrasive cloth after the polishing solution passes between the abrasive cloth and the subject.
In this invention, an abrasive cloth includes a polishing pad ,and a table includes a rotary table or a platen, and a holder includes top ring or polishing head or wafer carrier.
BRIEF DESCRIPTION OF THE DRAWING
A first embodiment consistent with the present invention is explained with reference to FIGS. 1 to 6.
The inventors of the present invention have identified that a pH value of a used slurry (a used polishing solution) is lower than that of an unused slurry, and that a polishing rate deteriorates with a lowering of a pH value of a slurry. The inventors have concluded that reducing slurry consumption only by circulating a used slurry is of limited value.
In this embodiment, a used slurry is not tried to be accumulated or maintained on a surface of an abrasive cloth but willingly discharged from the surface of the abrasive cloth.
Polishing apparatus 100 is provided with a rotary table 9 (table) rotated by a motor (not shown), an abrasive cloth 1 bonded on the top surface of rotary table 9 and a top ring 2 (holder) to hold and rotate a subject to be polished such as a semiconductor wafer. Top ring 2 is movably arranged. Polishing apparatus 100 is also provided with a polishing solution supplying mechanism 3 to supply a polishing solution onto abrasive cloth 1, and a plate 6 (discharger) to dam up a used polishing solution and discharge it off abrasive cloth 1. A first arm 20 supports supplying mechanism 3 arranged above abrasive cloth 1. A second arm 22 whose position and angle are changeable secures plate 6 above abrasive cloth 1 on rotary table 9. A third arm 24 supports top ring 2 which rotates on its axis.
Plate 6 may made of polycarbonate or fluorocarbon resin which are alcaliproof. However, other materials can be substituted. When worn, plate 6 can be replaced.
As to plate 6, a flat plate or a curbed plate may be used. Further, a circular plate, a spiral plate or a plurality of flat plates may be used. Moreover, an absorber to absorb a used polishing solution off abrasive cloth 1 or a blower to blow high-pressured air in a radially outward direction of the rotary table to blow a used polishing solution may be used instead of plate 6. Moreover, a suction unit to suck in a used polishing solution on abrasive cloth 1 may be used. Other ways to discharge a used polishing solution from the surface of abrasive cloth 1 may be substituted for plate 6.
An operation of polishing apparatus 100 will be explained next. A polishing solution is supplied onto a dripping position (supplying position) of abrasive cloth 1 while rotary table 9 with abrasive cloth 1 rotates. Plate 6 is arranged above abrasive cloth 1 in advance. Top ring 2 holding the subject to be polished rotates. Thus, the subject is polished.
A side wall of plate 6 facing top ring 2 is defined as an A-side (
Next, a position of plate 6 will be explained in detail with reference to
As shown in
In this embodiment, plate 6 is aligned with the angle θ ranging from −10 through −90 degrees.
The surface of abrasive cloth 1 has two areas divided by the line passing through the center of both the top ring 2 and the rotary table 9. When the dripping position is involved in one area, the plate 6 is arranged so as to be substantially involved in the other area in a plan view. In other words, a plane which passes through the rotational axes of both rotary table 9 and top ring 2 separates a region where almost all of plate 6 is involved from the other region where the dripping position is involved.
Using the method shown in this embodiment, the flow rate can be reduced by 70% without deteriorating the polishing rate.
A second embodiment is shown with reference to
A third embodiment is shown with reference to
A fourth embodiment is described next with reference to
As well as discharging a used slurry, an unused slurry can be recirculated and reused. In the first embodiment, plate 6 both discharges a used slurry and circulates an unused slurry.
In these embodiments, a polishing solution includes a fluid or a liquid containing an abrasive.
Numerous modifications of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the present invention can be practiced in a manner other than as specifically described herein.
Claims
1. A polishing apparatus, comprising:
- an abrasive cloth;
- a table to rotate the abrasive cloth;
- a holder configured to hold a subject to be polished against the abrasive cloth; and
- a discharger to discharge a polishing solution from the abrasive cloth after the polishing solution passes between the abrasive cloth and the subject
2. A polishing apparatus according to claim 1, further comprising a supplying mechanism to supply the polishing solution onto the abrasive cloth.
3. A polishing apparatus according to claim 1, wherein the discharger comprises a dam.
4. A polishing apparatus according to claim 1, wherein the holder comprises a top ring to rotate the subject, the discharger comprises a flat wall, and an inclination of the flat wall with reference to a plane which passes through a rotational axis of both the rotary table and the top ring is −10 through −90 degrees with the clockwise rotation viewed from the top face of the rotary table assumed to be positive.
5. A polishing apparatus according to claim 1, wherein the discharger comprises a blower.
6. A polishing apparatus according to claim 1, wherein the discharger comprises an absorber to absorb the polishing solution.
7. A polishing apparatus according to claim 1, wherein the discharger comprises a suction unit to suck in the polishing solution.
8. A polishing apparatus according to claim 1, wherein the abrasive cloth is bonded on the top surface of the rotary table.
9. A polishing apparatus according to claim 2, wherein the discharger comprises a plate to dam the polishing solution, and wherein the plate is up the polishing solution stream from the supplying mechanism.
10. A polishing apparatus according to claim 3, wherein the dam exerts force on the polishing solution in a radially outward direction of the rotary table.
11. A polishing apparatus according to claim 3, wherein the dam includes a flat wall to dam the polishing solution.
12. A polishing apparatus according to claim 3, wherein the dam includes a curved wall to dam the polishing solution.
13. A polishing apparatus according to claim 9, wherein the holder is a top ring to rotate the subject and wherein a plane which passes through a rotational axes of both the rotary table and the top ring separates the plate from the supplying mechanism.
14. A method of polishing a subject, comprising:
- rotating an abrasive cloth;
- providing a polishing solution between the subject and the abrasive cloth; and
- discharging the polishing solution from the abrasive cloth after the polishing solution passes between the subject and the abrasive cloth.
15. A method of polishing a subject according to claim 14, wherein rotating an abrasive cloth includes rotating an abrasive cloth on a rotary table.
16. A method of polishing a subject according to claim 15, wherein discharging the polishing solution includes exerting force on the polishing solution in a radially outward direction of the rotary table.
17. A method of polishing a subject according to claim 16, wherein exerting force on the polishing solution includes exerting force on the polishing solution using a plate.
18. A method of polishing a subject according to claim 16, wherein exerting force on the polishing solution includes blowing air toward the polishing solution in a radially outward direction of the rotary table.
19. A method of polishing a subject according to claim 14, wherein discharging the polishing solution includes absorbing the polishing solution.
20. A method of polishing a subject according to claim 14, wherein discharging the polishing solution includes sucking in the polishing solution.
Type: Application
Filed: Mar 25, 2005
Publication Date: Oct 6, 2005
Inventors: Takahiro Terada (Tokyo), Masaomi Nakahata (Kanagawa-ken), Yasutada Nakagawa (Kanagawa-ken)
Application Number: 11/088,786